Method and apparatus for reporting beam information in next-generation communication system

ABSTRACT

The present disclosure relates to a communication technique for convergence of IoT technology and a 5G communication system for supporting a higher data transfer rate beyond a 4G system, and a system therefor. The present disclosure can be applied to intelligent services (e.g., smart homes, smart buildings, smart cities, smart or connected cars, health care, digital education, retail business, and services associated with security and safety) on the basis of 5G communication technology and IoT-related technology. The present disclosure relates to a method and an apparatus for reporting beam failure-related information during beam measurement and reporting.

TECHNICAL FIELD

The disclosure relates to 5G wireless communication (or next generationwireless communication). In particular, the disclosure relates to aprocedure for performing beam measurement and reporting beam informationin a wireless communication system.

BACKGROUND ART

To meet the increased demand for wireless data traffic since thedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a “Beyond 4G Network” or a“Post LTE System”.

Implementation of the 5G communication system in higher frequency(mmWave) bands, e.g., 60 GHz bands, is being considered in order toaccomplish higher data rates. To decrease propagation loss of radiowaves and increase the transmission distance, beamforming, massivemultiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO),array antenna, analog beam forming, and large scale antenna techniquesare being discussed for the 5G communication system.

In addition, in the 5G communication system, there are developmentsunder way for system network improvement based on advanced small cells,cloud Radio Access Networks (RANs), ultra-dense networks,device-to-device (D2D) communication, wireless backhaul, moving network,cooperative communication, Coordinated Multi-Points (CoMP),reception-end interference cancellation, and the like.

In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and slidingwindow superposition coding (SWSC) as advanced coding modulation (ACM)and filter bank multi carrier (FBMC), non-orthogonal multiple access(NOMA), and sparse code multiple access (SCMA) as advanced accesstechnology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving into theInternet of Things (IoT) where distributed entities, such as things,exchange and process information without human intervention. TheInternet of Everything (IoE), which is a combination of IoT technologyand Big Data processing technology through connection with a cloudserver, has emerged. As technology elements, such as “sensingtechnology”, “wired/wireless communication and network infrastructure”,“service interface technology”, and “security technology,” have beendemanded for IoT implementation, recently there has been research into asensor network, Machine-to-Machine (M2M) communication, Machine TypeCommunication (MTC), and so forth. Such an IoT environment may provideintelligent Internet technology services that create new values forhuman life by collecting and analyzing data generated among connectedthings. The IoT may be applied to a variety of fields including smarthome, smart building, smart city, smart car or connected car, smartgrid, health care, smart appliances, and advanced medical servicesthrough convergence and combination between existing InformationTechnology (IT) and various industrial applications.

In line with these developments, various attempts have been made toapply the 5G communication system to IoT networks. For example,technologies such as a sensor network, Machine Type Communication (MTC),and Machine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be an example of convergencebetween the 5G technology and the IoT technology.

Meanwhile, in LTE, various downlink (DL) reference signals (RSs) aredesigned for a terminal to measure and estimate a channel from a basestation and uplink (UL) channels and UL control information (UCI) thatare reported based on the DL RSs. The UL channels being reported in LTEinclude aperiodic channel state information (CSI) reporting on physicaluplink share channel (PUSCH) (Aperiodic CSI Reporting using PUSCH) andperiodic CSI reporting on physical uplink control channel (PUCCH)(Periodic CSI Reporting using PUCCH). The UCI includes a channel qualityindicator (CQI), a precoding matrix indicator (PMI), a channel stateinformation—reference signal (CSI-RS), and HARQ-ACK/NACK. 5G New Radio(NR) using above-6 GHz frequency bands, as a new radio access technology(RAT), employs beam measurement-based terminal and base stationoperations for which no detailed reporting scheme has been agreed yet.

DISCLOSURE OF INVENTION Technical Problem

In NR, it has been agreed that a terminal performs measurement of beamsof a base station in such a way of measuring a reference signal receivedpower (L1-RSRP) based on a synchronization signal block (SSB) and aconfigurable CSI-RS, and it reports the L1-RSRP. It has also been agreedto use the following information and periodicities to report the L1-RSRPmeasured based on the SSB and CSI-RS.

-   -   For L1-RSRP and/or beam resource indicators (e.g. CRI or SSB        index) reporting for beam management, support the following UL        channels:    -   Short/long PUCC    -   PUSCH    -   Support the following reporting types for beam mgmt. on the        above channel    -   For Periodic, support long PUCCH and short PUCC    -   Semi-persistent—support all channels    -   Aperiodic—support PUSCH and short PUCC

That is, it has been basically agreed to use short and long PUCCHs andPUSCH for a beam measurement report. However, there has been nodiscussion about a method for a terminal to report a reception failureon some or all of the beams monitored for PDCCH for beam measurement andreporting. Although physical random access channel (PRACH) resourceshave been basically designed as part of a beam failure procedure, it hasnot been agreed how to quickly report a beam failure. There is thereforea need of a method for quickly reporting a partial or full beam failureusing PUCCH resources.

The disclosed embodiments propose a method for a terminal to report,when it fails to receive some or all of the beams being monitored forPDCCH, the beam failure. The proposed method may be implemented in sucha way of distinguishing between a partial beam failure, i.e., failing toreceive some of the beams for PDCCH configured to a terminal, and a fullbeam failure, i.e., failing to receive all of the beams for PDCCHconfigured to the terminal, and dealing with each of the partial andfull beam failures. In particular, the terminal transmits a beam failuremessage using periodic PUCCH resources.

The technical goals to be achieved through the disclosure are notlimited to just solving the aforementioned problems, and otherunmentioned technical problems will become apparent from the disclosedembodiments to those of ordinary skill in the art.

Solution to Problem

According to a disclosed embodiment, a beam information transmissionmethod of a terminal includes receiving downlink control informationfrom a base station on a downlink beam, generating, upon failure ofdecoding the downlink control information, beam information to reportfailure on the downlink beam, and transmitting the beam information tothe base station on a uplink control channel.

According to a disclosed embodiment, a terminal for transmitting beaminformation may include a transceiver configured to transmit and receivesignals and a controller configured to control to receive downlinkcontrol information from a base station on a downlink beam, generate,upon failure of decoding the downlink control information, the beaminformation to report failure on the downlink beam, and transmit thebeam information to the base station on a uplink control channel.

According to a disclosed embodiment, a beam information reception methodof a base station may include transmitting downlink control informationto a terminal on a downlink beam, receiving beam information indicatingfailure on the downlink beam from the terminal on an uplink controlchannel, identifying the failure on the downlink beam based on the beaminformation received on the uplink control channel, and transmitting thedownlink control information to the terminal on the reconfigureddownlink beam.

According to a disclosed embodiment, a base station for receiving beaminformation may include a transceiver configured to transmit and receivesignals and a controller configured to control to transmit downlinkcontrol information to a terminal on a downlink beam, receive beaminformation indicating failure on the downlink beam from the terminal onan uplink control channel, identify the failure on the downlink beambased on the beam information received on the uplink control channel,and transmit the downlink control information to the terminal on thereconfigured downlink beam.

Advantageous Effects of Invention

The method of a disclosed embodiment is advantageous in terms ofreducing uplink resource overhead for transmitting beam information byidentifying an exceptional situation for a terminal to receive beamsusing predetermined or periodically allocated resources with nonecessity for a base station to allocate special resources to aterminal. The method of a disclosed embodiment is also advantageous interms of reducing unnecessary power consumption, transmission, andsignaling by allowing a terminal to use resources already allocated.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating parameters and numerologies inaccordance with various PUCCH formats under discussion in acommunication system.

FIGS. 2A and 2B are diagrams illustrating resource configurations of aPUCCH format for use in a communication system

FIG. 3 is a diagram illustrating an exemplary UCI reporting scenario ofa terminal;

FIG. 4 is a diagram illustrating another exemplary UCI reportingscenario of a terminal;

FIG. 5 is a diagram for explaining a beam failure reporting procedure ofa terminal according to an embodiment;

FIG. 6 is a flowchart illustrating a beam failure reporting procedure ofa terminal according to an embodiment;

FIG. 7 is a diagram for explaining a beam failure reporting procedure ofa terminal according to another embodiment;

FIG. 8 is a flowchart illustrating a beam failure reporting procedure ofa terminal according to another embodiment;

FIG. 9 is a block diagram illustrating a configuration of a terminalaccording to a disclosed embodiment; and

FIG. 10 is a block diagram illustrating a configuration of a basestation according to a disclosed embodiment.

MODE FOR THE INVENTION

Exemplary embodiments of the disclosure are described in detail withreference to the accompanying drawings. The same reference numbers areused throughout the drawings to refer to the same or like parts.Detailed descriptions of well-known functions and structuresincorporated herein may be omitted to avoid obscuring the subject matterof the disclosure.

Detailed descriptions of technical specifications well-known in the artand unrelated directly to the disclosure may be omitted to avoidobscuring the subject matter of the disclosure. This aims to omitunnecessary description so as to make clear the subject matter of thedisclosure.

For the same reason, some elements are exaggerated, omitted, orsimplified in the drawings and, in practice, the elements may have sizesand/or shapes different from those shown in the drawings. Throughout thedrawings, the same or equivalent parts are indicated by the samereference numbers.

Advantages and features of the disclosure and methods of accomplishingthe same may be understood more readily by reference to the followingdetailed descriptions of exemplary embodiments and the accompanyingdrawings. The disclosure may, however, be embodied in many differentforms and should not be construed as being limited to the exemplaryembodiments set forth herein; rather, these exemplary embodiments areprovided so that this disclosure will be thorough and complete and willfully convey the concept of the disclosure to those skilled in the art,and the disclosure will only be defined by the appended claims. Likereference numerals refer to like elements throughout the specification.

It will be understood that each block of the flowcharts and/or blockdiagrams, and combinations of blocks in the flowcharts and/or blockdiagrams, can be implemented by computer program instructions. Thesecomputer program instructions may be provided to a processor of ageneral-purpose computer, special purpose computer, or otherprogrammable data processing apparatus, such that the instructions thatare executed via the processor of the computer or other programmabledata processing apparatus create means for implementing thefunctions/acts specified in the flowcharts and/or block diagrams. Thesecomputer program instructions may also be stored in a non-transitorycomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the non-transitorycomputer-readable memory produce articles of manufacture embeddinginstruction means that implement the function/act specified in theflowcharts and/or block diagrams. The computer program instructions mayalso be loaded onto a computer or other programmable data processingapparatus to cause a series of operational steps to be performed on thecomputer or other programmable apparatus to produce a computerimplemented process such that the instructions that are executed on thecomputer or other programmable apparatus provide steps for implementingthe functions/acts specified in the flowcharts and/or block diagrams.

Furthermore, the respective block diagrams may illustrate parts ofmodules, segments, or codes including at least one or more executableinstructions for performing specific logic function(s). Moreover, itshould be noted that the functions of the blocks may be performed in adifferent order in several modifications. For example, two successiveblocks may be performed substantially at the same time, or they may beperformed in reverse order according to their functions.

According to various embodiments of the disclosure, the term “module”,means, but is not limited to, a software or hardware component, such asa Field Programmable Gate Array (FPGA) or Application SpecificIntegrated Circuit (ASIC), which performs certain tasks. A module mayadvantageously be configured to reside on the addressable storage mediumand configured to be executed on one or more processors. Thus, a modulemay include, by way of example, components, such as software components,object-oriented software components, class components and taskcomponents, processes, functions, attributes, procedures, subroutines,segments of program code, drivers, firmware, microcode, circuitry, data,databases, data structures, tables, arrays, and variables. Thefunctionalities of the components and modules may be combined into fewercomponents and modules or further separated into more components andmodules. In addition, the components and modules may be implemented suchthat they execute one or more CPUs in a device or a secure multimediacard.

It may be advantageous to start the detailed descriptions of thedisclosed embodiments by setting forth the basic beam measurement andreporting procedure. The beam measurement and reporting procedure may beperformed on the basis of two kinds of signals as follows.

The first is an SS reference signal received power (SS-RSRP). TheSS-RSRP is defined as the linear average over the power contributions ofthe resource elements (REs) that carry secondary synchronization signalsand measured within a confined window duration of synchronizationsignal/physical broadcast channel (SS/PBCH) block measurement timeconfiguration (SMTC).

For SS-RSRP determination, a demodulation reference signal (DMRS) forPBCH or a configured CSI-RS may also be used in addition to the SS. Inthis case, the RSRP measurement based on such signals may be performedby linear averaging over the power contributions of the REs that carrythe DMRS for PBCH or CSI-RS. The RSRP measurement based on such signalsmay be performed in association with at least one of RRC states of theterminal, the RRC states including RRC_IDLE intra-frequency, RRC_IDLEinter-frequency, RRC_INACTIVE intra-frequency, RRC_INACTIVEinter-frequency, RRC_CONNECTED intra-frequency, and RRC_CONNECTEDinter-frequency.

The second is a CSI reference signal received power (CSI-RSRP). TheCSI-RSRP is defined as the linear average over the power contributionsof the REs that carry CSI-RS signals in a frequency band preconfiguredto the terminal a CSI-RS occasions. The CSI-RS is transmitted on aspecific antenna port of the base station, and the measured CSI-RSRP mayvary according to whether or not a reception diversity is applied in aone-port scenario and a two-port scenario. The CSI-RS for beammeasurement of the terminal may be configured with one port or two ormore ports. In this case, the RSRP measurement may be performed inassociation with at least one of RRC states of the terminal, e.g.,RRC_CONNECTED intra-frequency and RRC_CONNECTED inter-frequency.

The terminal may report a beam measurement result using both the PUCCHand PUSCH among uplink resources. To this end, various methods can beconsidered in accordance with the uplink frequency/time resources andreporting periodicity that the base station allocates to the terminal.

In NR, the PUCCH resources for measuring and reporting a beam state aredesigned as follows. Description are made hereinafter of the PUCCHformats (PF) being configured in radio resource control (RRC).

[PUCCH-resource-config-PF0] providing a set of resources for PUCCHtransmission with PUCCH format 0;

[PUCCH-resource-config-PF1] providing a set of resources for PUCCHtransmission with PUCCH format 1;

[PUCCH-resource-config-PF2] providing a set of resources for PUCCHtransmission with PUCCH format 2;

[PUCCH-resource-config-PF3] providing a set of resources for PUCCHtransmission with PUCCH format 3;

[PUCCH-resource-config-PF4] providing a set of resources for PUCCHtransmission with PUCCH format 4.

As listed above, 5 PUCCH formats from PUCCH format 0 to PUCCH format 4are considered in NR. A PUCCH may be classified into one of a shortPUCCH and a long PUCCH in accordance with the amount of PUCCH resources(i.e., number of symbols) configured by the base station in a slot ortransmission time interval (TTI), the PUCCH format being determined inaccordance with the size of the UCI to be transmitted in uplink, i.e.,1-2 bits or 3 or more bits.

FIG. 1 is a diagram showing a table of PUCCH formats defined withdifferent parameters and numerologies that are under discussion in NR;for example, PUCCH format 4 may be distinguished from other formats byan orthogonal cover code (OCC) and a cyclic shift operation in ascenario of multiplexing terminals. Meanwhile, it may be assumed thatPUSCH carries no separate UCI.

Each of the PUCCH formats has a UCI size that may change. Table 1 showsa UCI size and a number of DMRS symbols that are calculated under theassumption of a number of OFDM symbols in one resource block (RB), andthe UCI size may vary in accordance with the number of RBs carrying thePUCCH configured for the terminal. Table 1 shows exemplary values in thecase of a long PUCCH of 3 bits or more and a modulation order of QPSK.In Table 1, the UCI size of the PUCCH is a size taken after theinformation being carried by the UCI is encoded in accordance with eachinformation bit size.

TABLE 1 OFDM UCI size with hopping for 1 RB UCI size without symbols(number of DMRSs) hopping for 1 RB 4 OS  48(2)  72(2) 5 OS  72(2)  72(2)6 OS  96(2)  96(2) 7 OS 120(2) 120(2) 8 OS  96(4), 144(2) 144(2) 9 OS120(4), 144(2) 144(2) 10 OS 144(4), 192(2) 144(4), 192(2) 11 OS 168(4)168(4), 206(2) 12 OS 192(4) 192(4), 240(2) 13 OS 216(4) 216(4), 264(2)14 OS 240(4) 240(4), 288(2)

Accordingly, the UCI size may be changed according to the PUCCH format,whether the PUCCH is a short or long PUCCH, and the coding rate andmodulation scheme.

The UCI may include different information according to the type of thePUCCH format; for example, the UCI may include at least one of ascheduling request (SR), HARQ ACK/NACK, and CSI (CQI, RI, and PMI).Here, the UCI may further include information indicating a result of thebeam measurement performed by the terminal, the information including abeam resource indicator and L1-RSRP as a result of the beam measurementperformed by the terminal. Here, the beam resource indicator may be anSSB index (e.g., information included in PBCH) for the case ofperforming the beam measurement based on SSB and a CSI-RS resourceindicator (CRI) as an index indicating a CSI-RS for the case ofperforming the beam measurement based on a CSI-RS. The SSB index and theCSI-RS index may be carried in a common field or separate fields.

According to an alternative embodiment, the SSB index may be omitted inthe case where the SSB being monitored by the terminal is one of theresources of a serving base station.

Here, the beam resource indicator being transmitted by the terminal mayvary in accordance with the number of the beams configured for theterminal. That is, the base station may configure up to 64 beams for theterminal and, in this case, the beams can be distinguished by a numberof bits being calculated with log₂[L] (L is the number of bits). Thatis, the beam resource indicator may have a length of up to 6 bits.

The L1-RSRP has a length of 7 bits for indexing different ranges ofmeasurement result values. For example, the L1-RSRP may be reported withone of the indices listed in Table 2; although Table 2 shows specificranges of measurement result values and indices indicating therespective ranges, it is obvious that the ranges and the correspondingindices may be changed.

TABLE 2 measured quantity value index (L1-RSRP, dBm) 0 L1-RSRP < −140 1−140 <= L1-RSRP < −139 2 −139 <= L1-RSRP < −138 3 −138 <= L1-RSRP < −137. . . . . . 97 −44 <= L1-RSRP

Meanwhile, in the case where multiple beams are configured for aterminal, the terminal may report a maximum beam measurement value withone of the indices listed in Table 2, and a measurement value differencebetween the beam with the maximum beam measurement value and anotherbeam with 4 bits. The bit-size (or bitwidth) of the L1-RSRP beingreported by the terminal may be defined by 7+4k (k denotes a number ofbeams for reporting, k=0, 1, 2, . . . ). For example, in the case wherethe number of beams is 4 (i.e., 2 bits), the number of bits required forreporting the beam measurement result may be calculated as follows.2*1+7+4*1=13 bits  1-beam report:2*2+7+4*(2−1)=23 bits  2-beam report:2*3+7+4*(3−1)=33 bits  3-beam report:2*4+7+4*(4−1)=105 bits  4-beam report:6*64+7+4*(64−1)=24885 bits  6-beam report:

Meanwhile, the L1-RSRP may be reported to the base station along with abeam index (BI or CRI) via separate resources. The resources forreporting the L1-RSRP may be identified by the resources for the beamindex and at least one of time, frequency, and code domain resources.

FIGS. 2A and 2B are diagrams illustrating resource configurations of aPUCCH format for use in a communication system. The various PUCCHformats under discussion for use in the next generation communicationdiffer in radio resource configuration and DMRS location.

For example, PUCCH format 0 has no DMRS, and PUCCH formats 1 to 4 aredistinguished from each other by the location and ratio of DMRSs. In aspecific PUCCH format, the number of DMRSs varies according to whetherfrequency hopping is applied.

FIG. 2A shows exemplary implementations of PUCCH formats 1 and 2. Part(a) of FIG. 2A shows an exemplary implementation of PUCCH format 1 inwhich the shaded areas represent symbols to which the DMRS is mapped.Part (b) of FIG. 2A shows an exemplary implementation of PUCCH format 2in which the DMRS is mapped to the first, fourth, seventh, and tenthsymbols. The remaining radio resources may be used for transmitting UCIof PUCCH.

FIG. 2B shows exemplary implementations of PUCCH formats 3 and 4 inwhich frequency hopping may be applied. Part (a) of FIG. 2B shows aPUCCH resource configuration with DMRS locations in the case wherefrequency hopping is applied; in the drawing, N may denote a number ofsymbols for PUCCH. Part (b) of FIG. 2B shows a PUCCH resourceconfiguration with DMRS locations in the case where frequency hopping isnot applied. In the case where frequency hopping is applied as shown inpart (a) of FIG. 2B, one more DMRS symbol may be transmitted per hop onthe PUCCH resources; in the case where frequency hopping is not appliedas shown in part (b) of FIG. 2B, one or more DMRS symbols may betransmitted on the PUCCH resources. The remaining radio resources may beused for transmitting UCI of PUCCH.

Although the descriptions made with reference to FIGS. 2A and 2B aredirected to specific radio resource configurations, it is obvious thatthe radio resource configurations may be changed in design and format inaccordance with the improvement and implementation of the communicationsystem. It is also obvious that, if a new PUCCH format is proposed, thenumber and locations of the DMRSs can be changed.

Although the following embodiment is directed to the case where both theBI (or CRI) and L1-RSRP are transmitted to the base station, thedisclosure is not limited to the embodiment. In NR, a CQI size may bedetermined differently in various scenarios, and the CQI may be designedin a form similar to that in use for LTE.

Hereinbelow, descriptions are made of the beam measurement resultreporting periodicity and timing of a terminal. The beam measurementresult reporting periodicity and timing of the terminal may determine anencoding scheme. FIGS. 3 and 4 are diagrams illustrating exemplary UCIreporting scenarios of a terminal, the terminal having achievedsynchronization in the scenario of FIG. 3 and having achieved nosynchronization in the scenario of FIG. 4 .

In the case where the CQI and BI are reported at an interval of 2 ms asshown in FIG. 3 , the terminal may transmit an SR to the base stationalong with the CQI and BI. Here, the SR may have a length equal to orless than 2 bits and may be encoded independently of the CQI and BI. InFIG. 3 , assuming subcarrier spacing of 15 kHz, the terminal maytransmit the UCI using the OFDM symbols allocated for PUCCH, e.g., at aninterval of 1, 2, 5, 10, 20, 32, 40, 64, 80, 128, 160, 320, or 640 ms.

In the embodiment of FIG. 3 , the terminal may report the BI and thebeam measurement result (RSRP) along with the CQI at a synchronizedtiming. In this case, the terminal may transmit the BI at all or some ofCQI transmission occasions. That is, assuming that the CQI reportingperiodicity is 2 ms, the BI reporting periodicity may be a multiple of 2ms. In the embodiment of FIG. 4 , the terminal may report the MI and thebeam measurement result at a timing different from the CQI reportingtiming and, in this case, the BI reporting periodicity of the terminalmay be 2 ms or longer.

Hereinafter, descriptions are made of the BI reporting proceduresproposed in exemplary embodiments with reference to FIGS. 5 to 10 . Thedescriptions are directed to the operations of a base station and aterminal in the case where the terminal fails to receive some ofmultiple beams in a beam measurement procedure. In the followingdescriptions, if it is said that a beam fails, this may mean that aterminal fails to decode PDCCH on a specific beam. If it is said that aterminal identifies failure of some beams, this may mean that theterminal detects failure of some of DL beams or UL beams configured forthe terminal or failure of one of multiple DL-UL beam pair links (BPLs).

In a proposed embodiment, in order to notify the base station of a beamfailure in the BI reporting procedure, the terminal may transmit to thebase station UCI including a value or information indicating at leastone of following information items. In a proposed embodiment, the beamfailure notification procedure may be designed such that there is nonecessity to define a new PUCCH format.

-   -   information being transmitted for reporting beam failure

1-a) presence/absence of beam failed to receive

1-b) index of beam failed to receive

1-c) group index of beams failed to receive

2-a) presence/absence of new candidate beam(s)

2-b) index(es) of new candidate beam(s)

2-c) index(es) and beam quality(s) (e.g., L1-RSRP) of new candidate(s)

2-d) new candidate group index (a set of candidate beams)

Hereinbelow, a description is made of the transmission resources forbeam failure reporting and a method for utilizing the transmissionresources. A single-beam scenario is described first with reference toFIGS. 5 and 6 , and then a multi-beam scenario is described withreference to FIGS. 7 and 8 .

In the single beam scenario, DL beams 510 and UL beams 520 may beconfigured between a terminal (user equipment (UE)) and a base station(transmission and reception point (TRP) or gNB) as shown in part (b) ofFIG. 5 . The DL and UL beams 510 and 520 may form a beam pair link(BPL).

The terminal may receive a control resource set (CORESET) via a DL beam,and corresponding PUCCH resource may be allocated in association withthe CORESET. For such PUCCH resource, it may be necessary to configure aplurality of PUCCH formats.

In part (a) of FIG. 5 , the terminal receives a PDCCH in CORESET1 andperforms CQI measurement and beam measurement based on the received DLbeam. Next, the terminal transmits PUCCH carrying information on thereceive beam. Here, the terminal may simultaneously transmit the CSI(CQI/RI/PMI) and BI or the SR and BI using the PUCCH resources. Thesetwo cases are separately described.

A description is made of the simultaneous transmission of the CSI andBI. Here, the terminal may transmit the beam related information to thebase station in an implicit manner or an explicit manner. In theprocedure for the terminal to transmit the beam related information tothe base station in the implicit manner, if CSI and BI are reported atrespective periodicities that are synchronized, the CSI (CQI/RI/PMI) andBI are encoded together to be transmitted to the base station. That is,at least one UCI of the CSI may be encoded together with the BI, but ofcourse, the UCI may be encoded separately from the BI.

In an implicit method, assuming that a configuration is made to sweep 16beams and report two maximum values (best beam and second best beam),the terminal may transmit a wideband CQI (4*4 bits) and a BI (2*4+7(measurement value)+4 (difference value) bits) because of 16 beams beingconfigured for the terminal) to the base station. That is, in the caseof measuring 16 beams based on the SSB or CSI-RS and reporting 2 maximumvalues, the two beams having the maximum values may be changed such thatthe beam indices and the corresponding values to be reported by theterminal are changed, by way of example, from (beam index #1,measurement value)/(beam index #2, measurement) to (beam index #2,measurement value)/(beam index #3, measurement). This is the case wherethe beam RSRP being measured on the beam identified by beam index #1decreases such that the terminal performs measurement on the beamidentified by beam index #3 and reports the measurement result.

Here, the 16 beams may be partly or entirely included in a candidatebeam pool, and the base station may preserve and manage the beam indicesreported by the terminal in the candidate beam pool. If the terminalreports about the beam identified by beam index #3, the base stationsets the transmit beam to the beam identified by beam index #3 totransmit downlink signals to the terminal in the next scheduling cycle.This method may be called an implicit method in that the base stationnotices the beam failure on the beam identified by beam index #1 withoutany explicit indication from the terminal, and this method allows thebeam to be changed without modification of the existing beam reportingprocedure.

An explicit method is hereinafter described in detail. In the explicitmethod, the terminal may explicitly notify the base station of a beamfailure in the beam related information reporting procedure. Accordingto one of various embodiments, dropping of CQI may be considered. Forexample, the UE uses the CSI report field including 16 bits in PUCCH toreport the wideband CQI. The UE may use a BI field including 19 bits totransmit beam index and beam measurement values and difference values.At this time, the UE may drop (i.e, not transmit) the CQI to notify thebeam reception failure. The terminal may fill the corresponding fieldwith the information indicating the beam on which the beam failureoccurred instead of the CQI (i.e., skipping CQI transmission). In thisembodiment, the beam failure report may include at least one theaforementioned information items 1-a, 1-b, and 1-c.

The terminal may also transmit the index (4 bits) of the beam on whichit failed to decode a PDCCH (i.e., beam failure occurred) to the basestation. In this case, the terminal may pad the space, remaining afterfilling the BI in the field, with zeros because the CSI and BI should bedistinguished from each other within 16 bits for the existing CSIreport. Upon receipt of the beam related information from the terminal,the base station may identify the occurrence of the PDCCH decodingfailure based on detection of the zero-padded field and determine toselect a new beam. In this embodiment, the beam failure report mayinclude at least one of the aforementioned information items 1-b and1-c.

According to an alternative embodiment, the terminal may use the 16-bitCSI report field to report a wideband CQI and the 19-bit BI report fieldto transmit a beam index, a beam measurement value (maximum value), anda difference value (delta value). In this case, the terminal may dropthe CQI to transmit new candidate beam related information to the basestation. That is, the terminal may fill the corresponding field with thenew candidate beam related information (e.g., BI or CRI) instead of theCQI, and the base station assumes that the terminal monitors the newcandidate beam for PDCCH. Meanwhile, the term “candidate beam” denotes abeam excluding the beams configured for the terminal to monitor and, inthe case where a single beam is configured for the terminal, a beamdifferent from the corresponding beam.

According to an alternative embodiment, the terminal may extend the CSIfield (i.e., assign additional bits) to allocate additional resources orregard the RI/CQI field as a field for BI to transmit the BI.

The above embodiments are described with reference to FIG. 6 in whichthe terminal detects decoding failure in a CORESET on a specific BPL andidentifies occurrence of a beam failure at operation 610. Next, theterminal performs measurement at operation 620 to generate a CQI and/ora BI to be transmitted to the base station and encodes, at operation630, BI information associated with the beam on which the beam failureoccurred. In this operation, at least one of the above-described methodsmay be applied; for example, the terminal may drop the CQI and transmita beam index and/or a beam measurement value to the base station insteadof the CQI. It may also be possible for the base station to drop the CQIand transmit candidate beam related information to the base stationinstead of the CQI, padding the space remaining after filling theinformation on the beam on which the beam failure occurred with zeros inthe UCI. The CQI drop of the terminal may be encoded into apredetermined value in the corresponding field in an implementationmanner. For example, the field may be padded with zeros or predeterminedvalues (e.g., 111111).

Subsequently, the UE reports the beam-related information that hasfailed decoding to the base station by including it in the UCI (640),and receives the CORESET using the BPL changed by the base station(650). The base station selects a new beam based on the informationreported by the terminal on the failed beam and retransmits the CORESET.According to the above-described embodiment, when the UE fails to decodedownlink control information through a specific DL beam, the UE mayreport the failure of the DL beam to the base station through the ULbeam connected to the DL beam.

Hereinafter, a description is made of the method for transmitting the SRand BI on PUCCH resources according to an embodiment. According to anembodiment, the terminal may multiplex information on whether PDCCHdecoding failed into SR resources of the PUCCH resources to transmit theinformation to the base station. In the case of transmitting the SR tothe base station in an on-off key (OOK) mode, the terminal may use 1-bitinformation set to 1 or 0 to notify the base station whether or not abeam failure occurred. In this embodiment, the beam failure report mayinclude the aforementioned information item 1-a.

According to an alternative embodiment, the ACK/NACK and the SR may becyclically shifted by 180 degrees and 90 degrees respectively so as tobe identified separately on the PUCCH resources. Meanwhile, the BIinformation may be shifted by 450 degrees to be identified. Althoughspecific values are set forth by way of example in this embodiment, thecyclic shift angle is not limited thereto. For example, the cyclic shiftangle may be set to various values such as 60 degrees and 72 degrees.

Hereinbelow, a description is made of the multi-beam scenario withreference to FIGS. 7 and 8 .

In the multi-beam scenario, multiple BPLs may be configured between aterminal (UE) and a base station (TRP or gNB). Part (b) of FIG. 7 showsmultiple BPLs 710 and 720 each configured by pairing a DL beam and a ULbeam based on the beam correspondence or beam reciprocity, and part (c)of FIG. 7 shows the case of a plurality of BPLs 730-740 and 750-760 inwhich the DL beam and the UL beam are separated because there is no beamreciprocity or beam relevance.

The terminal receives multiple CORESETs on the multiple configuredbeams, and multiple corresponding PUCCH resources may be allocated inassociation with the multiple configured CORESETs. For each of the PUCCHresources, it may be necessary to configure a plurality of PUCCHformats.

In part (a) of FIG. 7 , the terminal receives a PDCCH in CORESET1 andperforms CQI measurement and beam measurement based on the received DLbeam. Next, the terminal transmits information on the received beam tothe base station on first PUCCH transmission resources. Similarly, theterminal receives a PDCCH in CORESET2 at the same or a different timingor on a different beam and performs CQI measurement and beam measurementbased on the received DL beam. The terminal may transmit the informationon the received beam on second PUCCH transmission resources. Theterminal may simultaneously transmit the CSI (CQI/RI/PMI) and BI usingthe PUCCH resources and, in this case, it may be necessary to change thebeam through one of an implicit beam changing operation and an explicitbeam changing operation, which are separately described in similarmanners as described with reference to FIGS. 5 and 7 .

In an implicit method, a PUCCH corresponds to a CORESET on each of themultiple beams. The terminal transmits the CSI (CQI/RI/PMI) and BI tothe base station on the PUCCH resources; the CSI and BI may be encodedtogether. That is, at least one of the CSIs of UCI may be encoded withBI and reported to the base station. Of course, CSI and BI may beseparately encoded and reported to the base station.

In an implicit method, assuming that a configuration is made to sweep 16beams (8 for transmitting CORESET A and 8 for transmitting CORESET B)and report 4 maximum values (best beam, second best beam, third bestbeam, and fourth best beam) per two PUCCH resources allocated in eachCORESET, the terminal may transmit a wideband CQI (4*4 bits) and a BI(4*4+7 (measurement values)+4 (difference values) bits) because of 16beams being configured for the terminal) to the base station. That is,in the case of measuring 16 beams based on the SSB or CSI-RS andreporting 4 maximum values, the four beams having the maximum values maybe changed such that the beam indices and the corresponding values to bereported by the terminal are changed, by way of example, from (beamindex #1, measurement value)/(beam index #2, measurement)/(beam index#3, measurement value)/(beam index #4, measurement value) to (beam index#2, measurement value)/(beam index #3, measurement value)/(beam index#7, measurement value)/(beam index #8, measurement value). This is thecase where the beam RSRPs being measured on the beams identifiedrespectively by beam index #1 and beam index #4 decrease such that theterminal performs measurement on the beams identified respectively bybeam index #7 and beam index #8 and reports the measurement result.

Here, the 16 beams may be partly or entirely included in a candidatebeam pool, and the base station may preserve and manage the beam indicesreported by the terminal in the candidate beam pool. If the terminalreports about the beam identified by beam index #3, the base stationsets the transmit beams to the beams identified respectively by beamindex #7 and beam index #8 to transmit downlink signals to the terminalin the next scheduling cycle. This method may be called an implicitmethod in that the base station notices the beam failure on the beamsidentified respectively by beam index #1 and beam index #4 without anyexplicit indication from the terminal and it allows the beam to bechanged without modification of the existing beam reporting procedure.

An explicit method is hereinafter described in detail. The explicitmethod may be implemented in several embodiments as described above.First, a 16-bit CSI report field configured per beam for CORESET A andCORESET B may be used for reporting a wideband CQI and a 39-bit BI fieldmay be used for transmitting a beam index, a beam measurement value, anda difference value (delta). Here, the terminal may drop the CQI of thePUCCH resources corresponding to CORESET A to notify the base station ofa reception beam failure for CORESET A. Likewise, the terminal may dropthe CQI of the PUCCH resources corresponding to CORESET B to notify thebase station of a reception beam failure for CORESET B. The terminal mayfill the corresponding field with the information indicating the beam onwhich the beam failure occurred instead of the CQI. In this embodiment,the beam failure report may include at least one the aforementionedinformation items 1-a, 1-b, and 1-c. The CQI drop of the terminal may beencoded into a predetermined value in the corresponding field in animplementation manner. For example, the field may be padded with zerosor predetermined values (e.g., 111111).

Next, the terminal may explicitly transmit to the base station an index(4 bits) of the beam corresponding to CORESET A in which PDCCH decodingfailed. In this embodiment, since the CSI information and the BI must bedistinguished within 16 bits for the existing CSI reporting, theterminal may transmit the fields excluding the BI by zero padding. Uponreceiving the beam-related information transmitted by the terminal, thebase station can determine that a PDCCH decoding failure has occurred bychecking the zero padded field, and can determine a new beam change. Inthe case of the present embodiment, at least one of 1-b and 1-c may beincluded as information transmitted when reporting the beam failuredescribed above.

According to an alternative embodiment, the terminal may use the 16-bitCSI report field of the beam for each CORESET to report a wideband CQIand the 39-bit BI report field to transmit a beam index, a beammeasurement value, and a difference value. In this case, the terminalmay drop the CQI to transmit new candidate beam related information tothe base station. That is, the terminal may fill the corresponding fieldwith the new candidate beam related information (e.g., BI or CRI)instead of the CQI, and the base station assumes that the terminalmonitors the new candidate beam for PDCCH. Meanwhile, the term“candidate beam” denotes a beam excluding the beams configured for theterminal to monitor and, in the case where multiple beams arepreconfigured for the terminal, a specific beam among the preconfiguredbeams. The candidate beam may also be a new beam that has not beenmonitored rather than the beams preconfigured for the terminal. In thisembodiment, the beam failure report may include at least one theaforementioned information items 2-b and 2-c.

According to another embodiment, the UE may explicitly transmit an index(4 bits) of a beam corresponding to A CORESET that has failed PDCCHdecoding. In this embodiment, since the CSI information and the BI mustbe distinguished within 16 bits for the existing CSI reporting, theterminal may transmit the fields excluding the BI by zero padding.Meanwhile, unlike the above-described embodiment, the UE may transmitthe index of the beam corresponding to A CORESET to the CQI field of thebeam corresponding to B CORESET. That is, a field excluding BI amongUCIs of B CORESET is zero padding and may be transmitted to a basestation including a beam index corresponding to A CORESET. In the caseof the present embodiment, at least one of 1-b and 1-c may be includedas information transmitted when reporting the beam failure describedabove.

According to an alternative embodiment, the terminal may use the 16-bitCSI report field of the beam for each of CORESET A and CORESET B toreport a wideband CQI and the 39-bit BI report field to transmit a beamindex, a beam measurement value, and a difference value. In this case,piggybacking the information notifying the base station of the receptionbeam failure in CORESET A on PUSCH resources may be considered. That is,the beam related information may be transmitted on the PUSCH resources.

The above embodiments are described with reference to FIG. 8 in which aterminal measures L1-RSRP on multiple preconfigured beams at operation810. If it is determined at operation 820 that PDCCH decoding succeededon all of the configured beams, the terminal transmits, at operation825, measured beam related information to a base station through apreviously scheduled PUCCH. If it is determined at operation 820 thatPDCCH decoding failed in a CORESET on a specific beam and if it isdetermined at operation 830 that the PDCCH decoding failed on all beams,the terminal declares beam failure at operation 840. If it is determinedat operation 830 that PDCCH decoding failed only on some beams, theterminal may generate beam related information according to one of theabove-described embodiments or a combination of at least two of theabove-described embodiments and transmit, at operation 850, the beamrelated information (information on the beam on which beam failureoccurred, e.g., at least one beam index, beam measurement value, anddifference value) to the base station through the existing PUCCH.

Although not explicitly shown in FIG. 8 , the terminal may receive theCORESET using a BPL changed by the base station based on the report fromthe terminal. That is, the base station may select a new beam based onthe information on the beam on which beam failure occurred amongmultiple beams configured for the terminal and retransmit the CORESET.The above-described procedure may be understood as a procedure for theterminal to notify the base station of the failure on a first beam amongthe multiple preconfigured beams or a first BPL through a second beam ora second BPL.

The operations of the terminal and the base station described in theembodiments described with reference to FIG. 3 may be performed inassociation with the radio resource configurations according to thePUCCH formats described with reference to FIGS. 2A and 2B. That is, theterminal may transmit information on the beam measurement result or beamfailure to the base station using one of the PUCCH formats describedwith reference to FIGS. 2A and 2B, which show the radio resourceconfigurations and locations and number of symbols to which a DMRS ismapped as described above.

FIG. 9 is a block diagram illustrating a configuration of a terminalaccording to a disclosed embodiment. In reference to FIG. 9 , theterminal may include a transceiver 910, a terminal controller 920, and astorage unit 930. In the disclosure, the terminal controller 920 may bedefined as a circuit, an application-specific integrated circuit, or atleast one processor.

The transceiver may communicate signals with a network entity. Forexample, the transceiver 910 may receive downlink signals for use inbeam measurement from a base station and transmit beam failure-relatedinformation to the base station.

The terminal controller 920 may control overall operations of theterminal as described in the above-disclosed embodiments. For example,the terminal controller 920 may control the transceiver 910 and thestorage unit 930 to perform the operations as described in theabove-disclosed embodiments with reference to the drawings. In detail,the terminal controller 920 may detect beam failure for a beam from thebase station and generate and transmit information related to thecorresponding beam to the base station.

The storage unit 930 may store at least one of informationtransmitted/received by the transceiver 910 and information generated bythe terminal controller 920.

FIG. 10 is a block diagram illustrating a configuration of a basestation according to a disclosed embodiment. FIG. 10 is a block diagramillustrating a configuration of a base station according to a disclosedembodiment. In reference to FIG. 10 , the base station may include atransceiver 1010, a base station controller 1020, and a storage unit1030. In the disclosure, the base station controller 1020 may be definedas a circuit, an application-specific integrated circuit, or at leastone processor.

The transceiver 1010 may communicate signals with other networkentities. For example, the transceiver 1010 may transmit downlinksignals such as a reference signal for use by a terminal in beammeasurement, a synchronization signal, or PDCCH. The transceiver 1010may be provided in the form of an RF unit including a modem.

The base station controller 1020 may control overall operations of thebase station as described in the above-described embodiments. Forexample, the base station controller 1020 may control the transceiver1010 and the storage unit 1030 to perform the operations as described inthe above-disclosed embodiments with reference to the drawings. Indetail, the base station controller 1020 may change or reconfigure abeam based on beam-related information received from a terminal.

The storage unit 1030 may store at least one of informationtransmitted/received by the transceiver and information generated by thebase station controller 1020.

Although the embodiments of the disclosure have been described usingspecific terms, the specification and drawings are to be regarded in anillustrative rather than a restrictive sense in order to help understandthe disclosure. It is obvious to those skilled in the art that variousmodifications and changes can be made thereto without departing from thebroader spirit and scope of the disclosure.

The invention claimed is:
 1. A method performed by a terminal in awireless communication system, the method comprising: receiving, from abase station, a reference signal on a downlink beam; generating beamrelated information for reporting a failure of the downlink beam, incase that a beam failure is detected based on the reference signal; andin case that a beam correspondence is satisfied and a plurality of beampairs are configured for the terminal, transmitting, to the base stationon a beam of a beam pair, the beam related information on a physicaluplink control channel (PUCCH) for periodic reporting of a beammeasurement result, wherein the beam measurement result includes ameasurement value and a differential value associated with the downlinkbeam, and a beam index of the downlink beam, wherein the beam relatedinformation indicates that the beam failure is detected and includes ascheduling request (SR), and wherein whether the beam correspondence issatisfied is determined based on the beam measurement result.
 2. Themethod of claim 1, wherein the beam pair is selected among the pluralityof beam pairs by excluding beam pair that includes the downlink beam,and wherein the beam related information includes candidate beaminformation on at least one beam to be monitored by the terminal, andthe at least one beam being different from the plurality of beam pairs.3. The method of claim 1, wherein a channel quality information, CQI, tobe reported on the PUCCH is dropped, or wherein an uplink payload otherthan the beam related information is zero-padded for the PUCCH.
 4. Themethod of claim 1, wherein the reference signal includes at least one ofa channel state information reference signal (CSI-RS) or asynchronization signal block (SSB).
 5. A method performed by a basestation in a wireless communication system, the method comprising:transmitting, to a terminal, a reference signal on a downlink beam; andin case that a beam correspondence is satisfied and a plurality of beampairs are configured for the terminal, receiving, from the terminal on abeam of a beam pair, beam related information on a physical uplinkcontrol channel (PUCCH) for periodic reporting of a beam measurementresult, wherein the beam related information is for reporting a failureof the downlink beam, in case that a beam failure is detected based onthe reference signal, wherein the beam measurement result includes ameasurement value and a differential value associated with the downlinkbeam, and a beam index of the downlink beam, wherein the beam relatedinformation indicates that the beam failure is detected and includes ascheduling request (SR), and wherein whether the beam correspondence issatisfied is determined based on the beam measurement result.
 6. Themethod of claim 5, wherein the beam pair is selected among the pluralityof beam pairs by excluding beam pair that includes the downlink beam,and wherein the beam related information includes candidate beaminformation on at least one beam to be monitored by the terminal, andthe at least one beam being different from the plurality of beam pairs.7. The method of claim 5, wherein a channel quality information, CQI, tobe reported on the PUCCH is dropped, or wherein an uplink payload otherthan the beam related information is zero-padded for the PUCCH.
 8. Themethod of claim 5, wherein the reference signal includes at least one ofa channel state information reference signal (CSI-RS) or asynchronization signal block (SSB).
 9. A terminal in a wirelesscommunication system, the terminal comprising: a transceiver configuredto transmit or receive a signal; and a controller coupled with thetransceiver configured to: receive, from a base station, a referencesignal on a downlink beam, generate beam related information forreporting a failure of the downlink beam, in case that a beam failure isdetected based on the reference signal, and in case that a beamcorrespondence is satisfied and a plurality of beam pairs are configuredfor the terminal, transmit, to the base station on a beam of a beampair, the beam related information on a physical uplink control channel(PUCCH) for periodic reporting of a beam measurement result, wherein thebeam measurement result includes a measurement value and a differentialvalue associated with the downlink beam, and a beam index of thedownlink beam, wherein the beam related information indicates that thebeam failure is detected and includes a scheduling request (SR), andwherein whether the beam correspondence is satisfied is determined basedon the beam measurement result.
 10. The terminal of claim 9, wherein thebeam pair is selected among the plurality of beam pairs by excludingbeam pair that includes the downlink beam, and wherein the beam relatedinformation includes candidate beam information on at least one beam tobe monitored by the terminal, and the at least one beam being differentfrom the plurality of beam pairs.
 11. The terminal of claim 9, wherein achannel quality information, CQI, to be reported on the PUCCH isdropped, or wherein an uplink payload other than the beam relatedinformation is zero-padded for the PUCCH.
 12. The terminal of claim 9,wherein the reference signal includes at least one of a channel stateinformation reference signal (CSI-RS) or a synchronization signal block(SSB).
 13. A base station in a wireless communication system, the basestation comprising: a transceiver configured to transmit or receive asignal; and a controller coupled with the transceiver configured to:transmit, to a terminal, a reference signal on a downlink beam, and incase that a beam correspondence is satisfied and a plurality of beampairs are configured for the terminal, receive, from the terminal on abeam of a beam pair, beam related information on a physical uplinkcontrol channel (PUCCH) for periodic reporting of a beam measurementresult, wherein the beam related information is for reporting a failureof the downlink beam, in case that a beam failure is detected based onthe reference signal, wherein the beam measurement result includes ameasurement value and a differential value associated with the downlinkbeam, and a beam index of the downlink beam, wherein the beam relatedinformation indicates that the beam failure is detected and includes ascheduling request (SR), and wherein whether the beam correspondence issatisfied is determined based on the beam measurement result.
 14. Thebase station of claim 13, wherein the beam pair is selected among theplurality of beam pairs by excluding beam pair that includes thedownlink beam, and wherein the beam related information includescandidate beam information on at least one beam to be monitored by theterminal, and the at least one beam being different from the pluralityof beam pairs.
 15. The base station of claim 13, wherein a channelquality information, CQI, to be reported on the PUCCH is dropped, orwherein an uplink payload other than the beam related information iszero-padded for the PUCCH.
 16. The base station of claim 13, wherein thereference signal includes at least one of a channel state informationreference signal (CSI-RS) or a synchronization signal block (SSB).